The method of experimental economics is applied to research of generation company bidding strategy and market behavior of uniform price and PAB auction mechanisms under different demand side response conditions with the multi-unit simultaneous auction model. The experimental results show that the market converges to adjacency of the perfect competition equilibrium under both mechanisms， but the average clearing price of PAB auction is higher than uniform price auction and the prices are more stable， so the payment to generation companies is larger. The market prices of both auction mechanisms are lifted when the demand becomes less elastic， but the market is still competitive when there is adequate capacity. The generation companies will take different bidding strategies under different auction mechanisms， and the competition among generation companies is more intense in uniform price auction.